


Percy Jackson and the Mortal Cup

by Forever_22



Series: Percy Jackson and the Mortal Instruments [1]
Category: Percy Jackson and the Olympians - Rick Riordan, The Heroes of Olympus - Rick Riordan, The Mortal Instruments (Movies), The Mortal Instruments Series - Cassandra Clare
Genre: Crossover, F/M, M/M, Mortal Cup, PJO, tmi
Language: English
Status: In-Progress
Published: 2017-11-02
Updated: 2017-11-02
Packaged: 2019-01-28 12:54:25
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,008
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/12607088
Author URL: https://archiveofourown.org/users/Forever_22/pseuds/Forever_22
Summary: When Simon Lewis, on a mission from the Clave, looses the Mortal Cup, a mundane teenager of the name Percy Jackson picks it up. Little did Simon know, the 'mundane' teenager, wasn't so mundane after all. Percy Jackson, Annabeth Chase and the rest of their friends take a little trip through history, through information even Annabeth did not know.While Percy and his friends try to find out who the cup belongs too, and how to give it back without loosing it themselves, or getting killed by creatures they never before face, Clary, Jace, Simon, Izzy, and Alec all have problems of their own... The Clave knows the cup is missing. The put a second deadline. If Simon were to not return the cup on Christmas Eve, four days after the deadline was issued, he would either be stripped of his runes and returned to the Mundane world, or killed.Will Percy Jackson be able to return the Mortal Cup to the Shadowhunters before Christmas? How will Simon find the one teenager who holds his life and his home in his hands in a city of thousands of people?





	Percy Jackson and the Mortal Cup

**Author's Note:**

> So, I've been wanting to do a Percy Jackson crossover FOREVER! And I finally have! I crossed over with.... *dramatically waves hands* THE SHADOWHUNTER CHRONICLES!!!!!! If you couldn't tell by the title, and the characters, and the relationships already! You guys r in for a WILD ride! Hope you enjoy! *kisses*

 

 

Walking past the empire state building, Simon looked up. He'd always loved the sight of the large building, taller than life, one of the tallest buildings in the world. The tallest building in New York. From the ground, the amazing height made the person looking up feel minuscule.

It used to make Simon feel like that before he'd ascended. Before he'd met Jace, his best friend's boyfriend, and Isabelle, his fiance, and Alec, his future brother in law, and Magnus, his future brother in law's husband. He felt tiny when he looked up before. Before he'd met the Clave, meeting in such a way that didn't get him sent to a prison cell built specially to keep the Jewish once-vampire in... It was a long, painful story.

Sighing, he moved on, barely hearing the soft clank of metal and amadas hitting the concrete behind him. After he was about a block away he put his hand into the bag at his side and froze. It was gone! The Mortal Cup was gone! Again!

He whipped around and started running, thankful for the glamour rune on his shoulder, making mundanes not see him barrel through them. He stopped at the side of the Empire state building, watching a teenager with black hair and sea green eyes. A teenager who couldn't be older than 18, pick up the Mortal Cup and look at it through the sunlight. Simon silently hoped he'd put it down, so he wouldn't have to tackle yet another mundane, but the kid showed the girl at his side that Simon hadn't noticed.

He couldn't hear what they said, but he was sure it wasn't good. The girl had blonde hair, like another shadowhunter Simon had met named Emma, and stormy grey eyes. She turned, and her eyes stopped at Simon, and he was grateful for the people that passed in front of him right at that moment. Then he wasn't so grateful.

As the people moved out of sight, so did the boy and girl. They were gone, lost in the sea of New Yorkers fighting to get to work early on a Monday morning. Simon stood up straight, running his hands through his brown hair, turning on his heel, breathing heavily. This couldn't be happening... A random mundane had just picked up the Mortal Cup and taken it!

It had been Simon's job to take it to the New York Institute, so Clary and Jace could take it to the Silent Brothers in the Silent City. Simon was screwed. He was so totally screwed.

  


***

 

Percy was still laughing when he and Annabeth got down to the bottom floor of the Empire State building. Annabeth had a small grin on her face, looking satisfied with herself. Zeus had granted all of the seven, Annabeth, Percy, Piper, Jason, Hazel, Frank, and Leo, one wish for completing another prophecy...

When it was Annabeth's turn, she'd asked to say something to one of the gods, without fear of punishment or retribution... And when the wish got granted, she turned to Hera and told her to fuck off.

Percy had never been more proud.

He wasn't the only one who had to be carried out of the throne room though, Leo and Piper both followed Percy's lead. When they got outside of the building, he still had a smile on his face. The rest of their friends had already left a few minutes before them, so Percy and Annabeth were alone.

Annabeth stopped him just after they'd exited the building. "What is that?"

He followed her pointed finger and raised an eyebrow, before bending down to pick up a cup laying on the ground. It was the size of a wine glass, with thick white... metal kind of stuff forming delicate designs around the glass, and giving a good hold for the person holding it. It looked pretty important.

"I have no idea... Maybe someone dropped it?"

Percy watched Annabeth look around, and followed her gaze when she stopped moving. She'd seen Simon, but Percy hadn't looked in time to see him. "Let's ask the others..." Annabeth said, sounding wary, before pulling Percy by his wrist after her.

They caught up with the Leo, Piper, and Jason easily, the three of them all still laughing about what Annabeth said to the goddess who had tormented Annabeth for quite a while. When they reached them, Piper was calmly taking the two boy's bets on how Hera would react.

"I bet she'll get so mad that Zeus will have to cage her just to keep true to the wish!" Leo shouted, and Piper's shoulders shook with a small snicker. "Hey, Percy, hey, Annabeth!"

Jason, who had started to open his mouth to put in his bet stopped walking, seeing the cup in Percy's hand. "What's that?"

"Good question." Annabeth sighed.

"Wait a second, Annabeth doesn't even know what it is?" Leo had a smirk on his face, joking around like he always did.

She shook her head, looking like it was the last thing she wanted to admit. “I’ve got no clue.”

“We were hoping one of you guys might know.” Percy shrugged.

The three of them all shook their heads in answer. “Well… What now?” Leo asked.

“I’ve still got a bet to place, so…” Jason smirked, but Annabeth cut him off.

“We could ask Chiron."

"Better than going around asking everyone in New York. That would take weeks!” Percy sighed.

“I’d say Months.” Jason said.

“Years, more like.” Annabeth said without a single second of hesitation.

“Instead of wasting more years of our life on stuff that we could probably have just asked about, let's go ask Chiron. Like Annabeth said!.” Piper said.

“Yeah… Let’s go.” Leo turned, before pushing Piper and Jason forward. Everyone started laughing at his insistence.

  


***

 

“You what!?” Jace said, his gold eyes practically bulging out of his head.

“I dropped the mortal cup on the sidewalk in front of the Empire State Building.” Simon trailed.

“Okay, so where is it now?”

“Two teenagers picked it up and disappeared before i could grab it back.”

Jace seemed to calm down, sitting down in an armchair in the library of the New York Institute. “Clary…”

“Yeah?” Clary sighed, sitting in another chair beside him, face buried in a book.

“Why did i give my blessing for Izzy to marry this idiot?”

“Well, you told me it was because you’re an idiot too.”

Jace didn’t seem happy with the answer, and he look scary calm. The kind of look someone gets when they seem calm, and yet you know that on the inside they’re ready to slit your throat with a variety of weapons and rip out your heart with their bear hands and eat it. That was the look that was on Jace’s face as he glared at his future brother in law. “Be glad my sister loves you. I think you can figure what you gotta do before the Clave finds out?”

“Get the cup back in time of the deadline without causing any mundanes to suspect the Shadow World.”

“And don’t let the mundane sell it on Ebay. They do that, and we’ll never get it back.” Clary said distractedly, hardly paying attention to the conversation.

Simon backed out of the library hesitantly, waiting until he was out of Jace’s view to let out a relieved sigh. He wasn’t going to die today! Then again, he doubted Clary would let Jace kill him. Maybe rough him around the edges a bit, but definitely not kill him in the way he knew Jace would fantasize killing him. In any of the ways Jace would fantasize his death.

Hopefully.

  


***

  


When Simon was gone, Clary put her book down and stood. She walked over to Jace, who was silently fuming, and sat on the arm of his chair. “You need to relax.” She put the hand on his shoulder and he leaned his head against her side.

“How? Izzy is in Venezuela fighting off new hordes of demons every hour. Alec and Magnus are in California. We have to take care of training for Raphael, and now this… I'm waiting for the Clave to send you off on a mission, or to say everyone has to come into Idris again, or start stripping Simon of his runes for losing the cup.”

Clary sighed as Jace put his arms around her waist, pressing his face to her side. Clary sighed, “You're the one who wanted to agree to be the head of the Institute.” He shrugged, and Clary laughed. “I love you.”

Jace smiled sheepishly up at her. The fading sunlight that peeked through the window turning his gold hair into an angelic halo, true to their blood… but not quite so true to the ruthlessness she'd seen him use in training or combat against a demon. His golden iris’ gleamed, and she could see then, just how stressed out he truly was. They were still human after all.

“Have you gotten any sleep?” Clary sighed, brushing hair out of his eyes.

Jace shook his head no, and Clary frowned. “How about this-?”

Her phone rang and Clary sighed. She picked it up and answered, “Iz?”

“Hey!”

“How's Venezuela?”

“Amazing! But… Clary. Since when do we have a kitchen door? And since when is it locked?” Clary dropped her head.

“Are you back already?”

“Yeah, Alec and Magnus are heading back too. Why?”

“I could ask you the same thing…”

“Well, I've taught all I can to the trainees in Venezuela about fighting in high heels that I can, and Alec and Magnus missed the kids! Duh! Now come let me in the kitchen!”

“No, talk later Iz, worry about settling in.”

“Okay!” She chirped, hanging up.

Jace raised an eyebrow, “The gang is back together again?”

Jace seemed to perk up at the thought of his siblings coming home. “Really!?”

“Yeah, Izzy's working on breaking into the kitchen, and Alec and Magnus are on their way.” Clary said it so nonchalantly that Jace almost didn't hear the 'Izzy breaking into the kitchen thing’.

“Izzy is doing what!?”

“Probably breaking down the kitchen door with her favorite heels.”

“Which ones? The black Jimmy Choo’s or the red Sergio Ross’?”

“The Jimmy Choo's. They're her ass kicking boots.” Jace smiled and stood.

“I'm gonna go save our new kitchen door. Care to join me?” Clary laughed and followed, shaking her head playfully.

  


***

  


When they got back to camp, Chiron and Dionysus, as usual, were playing some card game Percy didn't know. But, for the first time in awhile, specific dark haired boy sat beside them, chewing up a tin soda can…

“Grover!” Percy called, a huge smile on his face.

The satyr looked up. “Percy! Annabeth!” He stood and trotted over to his best friends. “You're back! Tyson is gonna be ecstatic!”

“Tyson’s here too!?” Percy looked very happy. He was happy. He had missed his half brother more than words could express, but the look on Annabeth’s face reminded him why they'd skipped food and came straight to camp. “First… Chiron? Have you ever seen anything like this before?” Annabeth pushed the cup into view as he spoke.

Chiron puts his cards down and picked it up. “No, no I haven't… But it's powerful, I can tell you that. Dionysus-”

“Don't touch that!” He god of wine slapped the empty wine glass from Chiron’s hand, leaving a stunned look on everyone's faces as they all watched the wine glass hit the grass just beyond the porch. Vines began to cover it, but Hazel, who popped up out of nowhere with Frank, picked it up.

“What? This? It's just a wine glass?” she said, while Piper and Annabeth shared a look that said 'a powerful one’.

“That's what they want you to think.” The grumpy old god muttered, drinking out of a cola can, frowning when it was empty and tossing it to Grover, who chomped on the tin willingly.

“Who wants us to think that…?” Leo said faintly.

“Nephilim.”

**Author's Note:**

> Did u guys likey??? I hope so! I had fun writing this actually! Please leave a Kudo or a comment below!
> 
> XOXO,  
> Funky Faith ( Always_Be_My_Number_22 )


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